Compression of femtosecond-pulse waveforms in spectral intensity filters

Femtosecond pulsed lasers are widely used in applied technologies, such as laser processing, nonlinear optical microscopy, and time-of-flight measurement, wherein narrowing the pulse duration is particularly important for improving the processing efficiency and signal-to-noise ratio of measurement systems. This paper proposes a method for shortening temporal pulse waveforms using spectral intensity filtering. Symmetrical spectral filtering was specifically applied at the central wavelength of the femtosecond pulsed laser spectrum. To investigate the pulse-narrowing effect, we numerically simulated the pulse duration as a function of the filtering width and cut-off wavelength position. The results of these simulations showed that the pulse duration decreased as the filter wavelength approached the central wavelength of the light. Furthermore, increasing the filter width reduced the pulse duration. Additionally, we implemented a spatial light modulator-based pulse-shaping system to realize a spectral intensity filter. We experimentally demonstrated that the duration of a telecom-band pulse was reduced by 9.8% when using a spectral intensity filter with a width of 1 nm.